Method for contouring gold tooth-crowns.



PATENTED SEPT. 3, 1907.

F. 'LA GHAPBLLE, METHOD FOR OO-NTOUBING GOLD TODTH oaowus.

APPLICATION FILED FEB. 20, 1907.

2 sums-SHEET 1.

N 865112. PATENTED SEPT. a 1907. F. LA GHAPELLE.

METHOD FOR GONTOURING GOLD TOOTH OROWNS.

APPLICATION FILED rum, 100v.

2 SHEETS-SHEET 2.

WITNESSES: IN VENTOR 2 w fZz PATENT OFFICE.

FRANCIS LA CHAPELLE, OF SAN FRANCISCO, CALIFORNIA.

METHOD FOR CONTOURING GOLD 'IOOTI -I-CROWNS.

Specification of Letters Patent.

Patented Sept. 3, 1907.

Application filed :cbruar 20, 1907. Serial No- 358,455.

To all whom it may concern:

Be it known that I, FRANCIS LA CHAPELLE, a citizen of the United States, residing in the city and county of San Francisco, and State of California, have invented new and useful Improvements in Methods for Contouring Gold Tooth-Crowns, oi which the following is a specification.

My invention relates to a method for forming seamless tooth crowns. Its object is to give a perfect contour to a crown in exact conformity with the tooth to which the crown is to be applied; to do the work of contouring in an eflicient and economical manner; and to avoid scams or ridges in the crown, such as are occasioned by the usual sectional molds now employed, or by other means commonly in use.

Having reference to the accompanying drawings: Figure 1 is longitudinal section of my mold with the plunger in full lines removed; and the plunger being shown inserted in dotted lines. Fig. 2 is a top end view, and Fig. 3 is a bottom end view of the mold. Fig. 4 is a section through the perforated guide block. Fig. 5 is an end view of the guide block. Figs. 6--7--8 are sectional views of the apparatus representing different steps in the practice of my method of contouring a tooth crown.

In the preliminary steps leading up to the point where the use of my invention begins, a gold cylinder is first roughly fitted to a metal tooth as a in the usual manner; the metal tooth a being a facsimile of the tooth to be crowned. The metal tooth a is of some suitable hard but easily fusible alloy, such as is commonly used in the art. This gold cylinder having been shaped to the metal tooth as well as it can be by means of a mallet, is then wrapped with tissue paper or like suitable covering to protect the tooth from the metal matrix in which it is subsequently treated. It is this subsequent treatment of the tooth and the apparatus for treating it that constitute my invention.

A represents a mold in the form of a steel cylinder having a cylindrical bore portion 2 for about half of its length and a tapered conical bore portion 3 for the remainder of its length. The drawings represent the full size of the various parts of my apparatus. It is manifest however that I can make the several parts of any size, and of appropriate shape or material.

l'is a plunger turned down and tapered at one end so as to fit freely inside of the mold A; the external contour of the plunger 4 corresponding to the interior of the cylinder, and the straight portion of the plunger being approximately of the same length as the straight 1 portion 2 of the cylinder. When the plunger is inserted into the mold as shown in dotted lines, Fig. 1, the lower tapered end of the plunger will preferably not extend to the bottom of the mold.-

In conjunction with this mold and plunger I use a steel block or cube B as shown in Figs. 4 and 5. This closed by means of the lead washer 7.

pressures.

cube or block has a hole 5 through it somewhat larger than the contracted lower end of the mold A. Around the opening 5 is formed an annular seat 6 to receive the mold.

In the practice of the invention the mold is partially filled with fine bird shot or leadshavings, or shredded lead; the small end of the mold being first temporarily The metal tooth with its crown in position having been wrapped in tissue paper as before stated, is placed in the midst of the lead packing 8 and covered over with more packing of the same character; the tooth being disposed about the middle of the'mass with the cervix of the tooth pointing upward. A lead washer 9 is then placed on top of the lead packing and inside of the mold.

The crown is now ready for the first pressure. The large end of the plunger 4 which just fits inside of the mold, it is then positioned on the Washer and the device placed in a suitable hydraulic press and the plunger moved to compact the lead packing 8 as shown in Fig. 7. During this first pressure the mold is supported on any flat resistant surface like the unperforated side of the block B, so that none of the contents of the mold can escape through the lower opening. The mold is then taken from the press and the plunger reversed so that the conical end of the plunger points downward. The mold is then placed over the opening 5 in block B with the .lower end of the mold resting in the seat 6; the mold and the opening 5 being in axial alinement. The plunger is then subjected to a second and even greater pressure than first given to it, which results in the entire contents of the mold being pushed down into the hole 5 in the block B as shown in Fig. 8; the straight portion of the plunger forming a guide during both pressure operations to indicate the proper limits of movement of the plunger. After the tooth with its crown has been pushed through the mold in the manner described, it is taken out of its paper coating and melted out of the crown, whereupon the latter after suitable trimming and burnishing is ready for use.

Considerable practice with this invention has demonstrated the advisability and the nature of the two During the first pressure the lead packing 8 is compacted into almost a solid mass, which latter is further contracted by pushing it through the restricted opening in the lower end of the mold. The first pressure in compacting the mass of comminuted lead serves to push the surplus gold toward the gum portion or cervix of the tooth. This first pressure produces an action on the crown similar to drawing a glove onto the hand. The second pressure, during which period, the tooth and crown are shoved through the small end of the mold, acts to press the gold laterally, to cause it to hug snug in every part and assume the exact contour of the metal tooth. The actual contouring mightbe said to be effected by this second pressure. The tapered sides of the mold equalizes the pressure on all sides of the tooth and contours the crown so that when the tooth is melted out of the crown, the latter needs only a little trimming around its edges to remove the surplus gold which had been crowded back during the first pressure. The first pressure if too great will bend the metal tooth and upset it and get it out of shape. Thus while each of these pressures amount to several tons per square inch, it is important that the first pressure be not overdone It will be manifest therefore that pressing in a closed mold is only a part of my invention; the chief thing being a final pressure and the pushing of the previously compacted mass through the small opening in the mold.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is

pressure to cause the metal bed and its contained metal tooth and crown to move together and the metal of the bed to flow laterally and thereby press the proposed crown into the irregularities of the metal tooth.

2. The method herein described of contouring tooth crowns, said method consisting in supporting a partially shaped crown upon a metal i'ac-simile of the tooth in the midst of a body of mobile material, then compacting said material by pressure, and then forcing the material and the tooth crown embedded therein through a chamber of gradually reducing area to cause the material. to flow laterally and complete the crown by shaping it to the irregularities of the metal fac-simile.

3. The method herein described of contouring tooth crowns, said method consisting in supporting a partially shaped crown upon a metal iac-simile of the tooth in the midst of a body of granulated soft metal, then compacting the granules to form substantially a solid mass thereof, then forcing the metal mass and its contained crown and metal tooth through a restricted passage to cause the metal to flow in lateral planes to thereby complete the shaping of the crown by forcing the gold into the irregu larities of the metal fac-simile, and then fusing the metal fac-simile.

In testimony whereof I have hereunto set my hand in presence of two subscrlbine; witnesses.

FRANCIS LA CI'IAIELLE.

Witnesses FRANK I). TRICOU, HENRY P. TltICOU. 

